The discussion revolves around the motion of the Milky Way and other galaxies in the Local Group, exploring concepts of orbit, gravitational binding, and the dynamics of larger cosmic structures such as the Great Attractor. Participants examine whether galaxies orbit a common center, the implications of cosmic expansion, and the nature of movement on a universal scale.
Participants express multiple competing views regarding the nature of galaxy motion, the appropriateness of terms like "orbit," and the future of the universe. The discussion remains unresolved, with no consensus on several key points.
Limitations include the dependence on definitions of motion and orbit, as well as unresolved questions about the nature of the Great Attractor and the universe's ultimate fate.
PhanthomJay said:Does the Milky Way galaxy, along with several other galaxies in the Local Group, orbit about the centre of that Local Group, and does the center of the Local Group orbit about some other center, etc.??, or is it just the stars that orbit their galactic centers?
PhanthomJay said:OK, thanks. I gather that the Milky Way and our Local Group of galaxies is moving toward some mysterious huge mass known as the Great Attractor, and that such motion is along a space-time geodesic, rather than an orbiting type circular or elliptical motion around it?'
PhanthomJay said:If the Milky Way is 'orbiting' about the center of the Local Group, and that center in turn is moving at some ridiculous speed toward the Great Attractor, is the Great Attractor also moving toward some other ridiculously large massive cluster, or does the buck stop there and the Attractor is just sort of hanging in free space (not including space-time expansion) without any particular motion??
Chronos said:This is all well and good, but, does not suggest the universe is rotating. The axis of rotation of local galaxies are randomly distributed. There is no preferred distribution as suggested if the universe itself was rotating.
PhanthomJay said:Let's forget the words 'rotation' or 'orbit'.The Earth is moving around the sun. The sun is moving around the center of the Milky Way. The Milky way is moving around the center of the Local Group. The center of the Local Group is moving toward that Great Attractor. Everything is moving. I see no reason why the Great Attractor is also not moving toward something, and that something must be moving toward something else. Movement without end, Amen?
Pretty hard to tell. It gets pretty sketchy to decide what is movement at this scale. Since we don't really know what this Great Attractor is or where it is, you can deduce that we're sort of poking about in the dark.PhanthomJay said:...does the buck stop there and the Attractor is just sort of hanging in free space (not including space-time expansion) without any particular motion??
Bluedust said:And then eventually they will all attract together again and cause another Big Bang?
DaveC426913 said:That scenario's likelihood is vanishing rapidly (if not completely debunked already). The expansion of the uiniverse is overwhelming the attraction on larger scales. The Big Freeze is looking to be the more likely. We end up in an observable universe devoid of any other galaxies but those gravitationally bound to us. Beyond a few million light years, the universe is completely barren.